1. Field of Invention
The present invention relates to a semiconductor device and a manufacturing method thereof, and specifically to a technique of forming semiconductor elements, which have excellent performance and which employ a substantially single-crystalline semiconductor film, on a large-sized substrate.
2. Description of Related Art
A related art method of manufacturing a thin film semiconductor transistor represented by a polycrystalline silicon thin film transistor (p-SiTFT) at a relatively low temperature includes a method of manufacturing a thin film transistor by heating an amorphous silicon film with a laser to form a polycrystalline silicon film, forming a gate electrode out of the polycrystalline silicon film as a semiconductor film, and forming interconnections out of a metal thin film. However, in this method, since it is difficult to control energy of the laser beam and deviation occurs in a feature of the semiconductor film to be manufactured, a technique of growing a substantially single-crystalline silicon film without causing the above problem, in place of the polycrystalline silicon film, has been suggested in the related art. This technique is described in a document entitled “Single Crystal Thin Film Transistors”, IBM TECHNICAL DISCLOSURE BULLETIN, August 1993, pp. 257-258, or a document entitled “Advanced Excimer-Laser Crystallization Techniques of Si Thin-Film For Location Control of Large Grain on Glass”, R. Ishihara et al., proc. SPIE 2001, vol. 4295, p. 14-23.
In theses documents, it is disclosed that fine holes (grain filters) are formed in an insulating film on a substrate. An amorphous silicon film is formed on the insulating film and in the fine holes. A laser is then applied to the amorphous silicon film, the amorphous silicon in bottom portions of the fine holes is held to be in a non-melted state and the amorphous silicon in portions other than the bottom portion is made to be in a melted state. Crystal growth using the amorphous silicon held in a non-melted state as crystal nucleuses is caused, thereby forming the substantially single-crystalline silicon film.